We also report some qualitative results of SE [1]} in Figure REF . As is shown in the figure, one common failure case of SE is that when the length of irregular objects is longer than a threshold, the object will be split into multi instances, for example, the wire in Figure REF . We think that's because SE will regress a circle of the target instance and then calculate its IoU with the mask for supervision. However, for long and thin irregular objects, the radius of the center circle can not reach the length of the target object, leading to a multi-split of a long instance. Also, instances that share the same center may cause ambiguity to SE, such as hanger and fence in Figure REF . Moreover, many centers of irregular objects lie outside the mask, making it hard to match them to the objects themselves.
